The cylinder bore of an engine is finished by honing with grindstones after boring with cutters. The boring and honing for forming the inner peripheral surface of a work bore such as the cylinder bore has heretofore been performed in separate steps with separate tool heads mounted on separate shafts. Consequently, it is difficult to shorten the working time and to improve the working efficiency, and a great deal of machinery and devices must be provided.
Honing is performed by rotating and axially reciprocating a tool head provided with grindstones. But according to the conventional honing operation, the tool head which is reciprocated by a reciprocating mechanism is maintained in a floating state by means of a universal joint, and by this floating action the grindstones are permitted to follow the inner peripheral surface of a work bore to effect honing. Therefore, an attainable machining speed is inevitably limited, and it has thus been impossible to effect honing at high speeds and with high efficiency.